United Nations weapons inspectors are back in Baghdad for the first time in four years to begin implementing a tough new UN resolution aimed at disarming Iraq.

BBC News Online looks back at the last UN arms mission to Iraq, and the events leading up to the withdrawal of inspectors at the end of 1998.

In April 1991, immediately after the Gulf War had finished, the UN Security Council passed a series of resolutions authorising the inspection and destruction of Iraq's arsenal.

What unfolded over the next seven years, according to the weapons inspectors from the UN's Special Commission (Unscom), was an almost farcical tale of cat and mouse.

After a string of false dawns, with the termination and subsequent resumption of inspections, the UN finally lost its patience with Iraqi leader Saddam Hussein, withdrawing the team on 17 December, 1998.

Within hours the allied bombings of Operation Desert Fox were under way.

Inspectors turned away

The history of Unscom was characterised by Iraq's persistent refusal to co-operate with the team, and incident after incident of apparent obstruction and deceit.

The inspectors said they were not provided with "unfettered access" to any site in the country, as had been agreed.

The team was pulled out just before Desert Fox began

Central to the mission's mandate were the unannounced visits to suspected storage facilities.

Inspectors were frequently turned away at the door - as was the case at Saddam Hussein's presidential palaces. By December 1997, inspectors said they had been formally told that these sites were off limits.

On other occasions, the Unscom teams would be kept waiting at the front gates to sites, they reported, while trucks and equipment left by the back.

They also alleged that the Iraqis tampered with their equipment, which included state-of-the-art sensors and remote cameras.

One of the major problems the inspection team confronted was the dual nature of many of the sites they inspected.

It was suspected that fermenters and centrifuges used every day in dairies, wineries and pharmaceutical houses were quickly converted for churning out weapons, and then switched back to innocent purposes.

Iraqi objections

Iraq was meanwhile complaining about the make-up of the team - which it said included too many Americans.

Chief arms inspector Richard Butler complained of obstruction

In October 1997, Baghdad barred American weapons inspectors. It accused the leader of one of the teams, US national Scott Ritter, of spying for the Americans.

Over the next 12 months, Iraq blocked inspections on two occasions, but in November of 1998, Baghdad said the team could return.

Within a month, the UN had pulled the inspectors out of the country, after team leader Richard Butler declared the Iraqis were still refusing to co-operate.

What remains

The mission was not, however, without some success.

During its spell in Iraq, weapons inspectors surveyed more than 1,000 sites and destroyed missiles, supergun components and chemical munitions, as well as biological weapon production equipment and materials.

Mr Butler concluded that Iraq had allowed the inspectors to find weapons, but only those that were the least up-to-date, and therefore of the least use.

It will be the task of the new inspections body, Unmovic, to find whatever its predecessor was unable to uncover.